Airlines Charge Thousands Extra for a Few Inches of Legroom on Long Flights

FRANKFURT—For fliers, the ideal seat is usually in first or business class. For airlines, the sweet spot on long-haul flights is, increasingly, farther back in the plane.

A new hybrid class, called premium economy, is appearing on more planes due into its attractive economics. The seats generally give passengers a bit more space than traditional coach and often come with extra amenities like better food. Tickets are pricier than for...